ARCHIVED REPORTS_2013 ANNUAL REPORT

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Nestle USA, Inc., Ripon, California March 26, 2014 2013 Annual Report since river stage has a significant effect on regional groundwater levels above the Corcoran unit. • The model is designed with five specific recharge zones representing all of the engineered recharge basins in the lagoons area. • The model was simplified by assuming homogeneous hydraulic conductivity in each layer. The Parameter Estimation Program (PEST), which includes powerful inverse modeling routines and assessment capabilities, was used to calibrate the hydraulic conductivity and storage parameters for the Upper and Intermediate aquifer layers. • On a model-wide basis, the scaled residual standard deviation for the new model is 6.5 percent (industry standard of 10 percent or less), which is an improvement over the 2007 model (12 percent) and the 2011 model (10 percent). In 2013, the new model was used as a predictive tool for the following applications: 1) capture zone analysis in the M-10A area to assess potential extraction well scenarios, and 2) animation of groundwater elevation contours and velocity over time for the Upper and Intermediate aquifer zones to visualize groundwater flow patterns during changes in river stage and basin recharge. The process for developing the 2013 model was presented to the RWQCB during a WebEx meeting on December 3, 2013. Model animations were included in the presentation to RWQCB staff during the December 12, 2013, meeting. 4.8 NPDES/WATER DISPOSAL ALTERNATIVES ECM evaluated several water disposal alternatives based on discharge from the current IRAP system and future extraction of groundwater when the RAP is approved. ECM initiated the NPDES permit application process to discharge to the Stanislaus River as one of the disposal options. During the December 2013 meeting with the Ripon Team, RWQCB staff recommended reinjecting the treated water and offered to help Nestle obtain a WDR permit. Reinjection of treated water has the dual benefit of recharging the aquifer (beneficial use of resources) and potential reduction in cleanup time. Currently, ECM is preparing the WDR permit application for submittal to RWQCB at the end of First Quarter 2014. 5 CONCLUSIONS The monitoring and remediation information provided in the 2013 Annual Report supports the conclusions presented below. These conclusions fall into the following categories: • Groundwater Monitoring and Sampling (Section Error! Reference source not found.); • Groundwater Extraction and Treatment (Section Error! Reference source not found.); and • Migration Control (Section Error! Reference source not found.). 5.1 GROUNDWATER MONITORING AND SAMPLING 1. The groundwater flow direction in all three aquifers (Upper, Intermediate, and Lower) has generally remained consistent with conditions observed during previous years. 20